patch applied (ghc-6.12/ghc): Fix Trac #3591: very tricky specialiser bug

[Ian Lynagh]

Fri Oct 23 09:15:51 PDT 2009  simonpj at microsoft.com
  * Fix Trac #3591: very tricky specialiser bug
  Ignore-this: 705bf8d79fdf89b0a98f278de4303a8d
    
  There was a subtle bug in the interation of specialisation and floating,
  described in Note [Specialisation of dictionary functions]. 
    
  The net effect was to create a loop where none existed before; plain wrong.
    
  In fixing it, I did quite a bit of house-cleaning in the specialiser, and
  added a lot more comments.  It's tricky, alas.

    M ./compiler/basicTypes/Id.lhs -1 +6
    M ./compiler/specialise/Specialise.lhs -173 +301

View patch online:
http://darcs.haskell.org/ghc-6.12/ghc/_darcs/patches/20091023161551-1287e-6f21e6c3b95d667fcbe7237bd3c7709814916905.gz